1. Field of the Invention
The present invention relates to a display panel socket, which can be preferably used for an inspection of the display quality of a liquid crystal display panel, a plasma display panel, etc.
2. Description of the Related Art
In general, in the manufacturing process of a liquid crystal display panel, the display panel is inspected for display defects, display quality, etc. before connection of IC tabs for drive use and other peripheral circuits. In this case, in order to turn on the display panel, it is necessary to bring contact members into contact with the electrode terminals arranged on a substrate of the display panel. Therefore, conventionally, pin shaped or wire shaped probes, flexible wiring boards comprised of plastic film substrates on which contactor patterns are formed, etc., have been used as the members for contact with the electrode terminals. Along with the rise of density of electrode terminals and the increasing fineness of the pitch, the trend is toward use of flexible wiring boards from the viewpoint of the reliability of contact with the electrode terminals, facility of handling, manufacturing costs, etc.
Further, Japanese Unexamined Patent Publication (Kokai) No. 08-220175 and Japanese Unexamined Patent Publication (Kokai) No. 08-278339 of the present assignee disclose a display panel socket capable of performing the inspection of the display quality of the display panel and an aging test for inspecting the durability of the display panel under a high temperature. This display panel socket has a substantially rectangular socket body provided with a panel positioning means for holding the substrate of the display panel. The socket body is provided with film attachment boards extending along directions of arrangement of the electrode terminals on the substrate of the display panel via position adjusting means so that the positions thereof can be adjusted in the longitudinal direction. Onto the film attachment boards, flexible wiring boards having contactors for contact with the electrode terminals of the display panel are attached. Accordingly, by adjusting the positions of end portions of the film attachment boards by the position adjusting means, the positioning between the electrode terminals on the substrate of the display panel and the contactors on the flexible wiring boards attached to the film attachment boards can be carried out on the socket body. Then, by pressing the substrate of the display panel from the rear of the electrode terminals by a panel pressing member provided on the socket body, the display panel can be fixed to the socket body and, at the same time, the electrode terminals and the contactors can be held in the contact state by a required contact pressure.
However, in the above-mentioned conventional display panel socket, each of the position adjusting means for adjusting the positions of the end portions of the film attachment boards has a biasing spring for pressing one end portion of the film attachment board in the longitudinal direction and an adjustment member abutting against the other end portion of the film attachment board against the pressing force. Therefore a compressive load will act upon the two ends of the film attachment board in the longitudinal direction and warping will occur in the film attachment board due to the compressive load. Thus, it is considered that an adverse influence will be exerted upon the precision of positioning the contactors of the flexible wiring board attached to the film attachment board and the electrode terminals on the display panel, and upon the durability. Further, in a liquid crystal display panel, generally electrode terminals are arranged along two sides or along three sides of the substrate. In the conventional display panel socket mentioned above, it is necessary to arrange the biasing spring and the adjustment member of a position adjusting means at the corner portion of the socket body at one end of the film attachment board and the corner portion of the socket body at the other end of the film attachment board, so there arises a problem that if it is intended to arrange a biasing spring or an adjustment member of a position adjusting means of another film attachment board at the corner portions of the socket body, the size of the socket body is enlarged.
Accordingly, an object of the present invention is to provide a display panel socket which can be easily applied to even a display panel in which electrode terminals are arranged at two sides or three sides of the substrate.
To attain the above object, according to the present invention, there is provided a display panel socket provided with a substantially rectangular socket body, a panel positioning means for positioning the substrate of the display panel with respect to the socket body, film attachment boards attached to the socket body in parallel to the directions of arrangement of electrode terminals of the display panel via position adjusting means so that the positions can be adjusted, and flexible wiring boards which are attached to the film attachment boards and have contactors to be brought in contact with the electrode terminals of the display panel, the display panel socket characterized in that each of the position adjusting means has a biasing spring for spring biasing a film attachment board in one direction among the longitudinal directions of the same and an adjustment member for adjusting the position of an end portion of the film attachment board against the spring force and in that both of the biasing spring and the adjustment member are arranged on the socket body so that they act upon the same end portion of the film attachment board.
In the display panel socket having the above configuration, by adjusting the position of the film attachment board with respect to the socket body by the position adjusting means, the positioning between the electrode terminals of the display panel held by the panel positioning means of the socket body and the contactors of the flexible wiring board attached onto the film attachment board can be carried out. In addition, both of the biasing spring and the adjustment member constituting the position adjusting means are arranged on the socket body so as to act upon the same end portion of the film attachment board, therefore a compressive force due to the biasing spring and the adjustment member can be prevented from being applied between the two ends of the film attachment board. Accordingly, occurrence of warping of the film attachment board due to the compressive force can be reliably prevented, so a reduction of the positioning precision between the electrode terminals and the contactors of the flexible wiring board can be prevented over the entire arrangement of the electrode terminals of the display panel. Further, since both of the biasing spring and the adjustment member constituting the position adjusting means are arranged on the socket body so as to act upon the same end portion of the film attachment board, on the socket body on the other end of the film attachment board, space for arrangement of a biasing spring and adjustment member constituting the position adjusting means of another film attachment board can be easily secured on the socket body at the other end portion of the film attachment board. Accordingly, a display panel socket which can be applied without causing interference between the position adjusting means and the enlargement of size of the socket body can be provided with respect to various types of display panels in which electrode terminals are arranged at two sides or three sides of the substrate.
Preferably, on the socket body, elongated grooves, for holding the film attachment boards so that they can slidingly displace in their longitudinal direction, are formed along at least two adjoining sides of the socket body. The elongated grooves formed at the two sides extend crossing each other. The adjustment members of the position adjusting means have end pieces which are slidably accommodated in the elongated grooves and attached to the end portions of the film attachment boards. Abutment pieces which are accommodated in the end portions of the elongated grooves so as to abut against inclined end portions are formed at the end pieces, and adjustment screws are provided for displacing the abutment pieces in a depth direction of the elongated grooves. The end pieces are formed so that two end pieces can freely slidingly displace while crossing each other at the crossing portion of the elongated grooves when attached to the film attachment boards. Spring holding portions for holding the biasing springs of the position adjusting means are provided near the crossing portion of the elongated grooves of the socket body corresponding to the elongated grooves.
According to the above configuration, the end portions and abutment pieces constituting the adjustment members of the position adjusting means can be accommodated in the end portions of the elongated grooves for accommodating the film attachment boards, therefore a display panel socket which is compact and can arrange the film attachment boards at appropriate positions so that the positions can be adjusted in accordance with the form of arrangement of the electrode terminals of the display panel can be provided.
Further preferably, the elongated grooves are formed along three sides of the socket body; and the crossing portions of the elongated grooves are formed at two positions.
According to the above configuration, even in a case where there are electrode terminals at one side of the display panel and either the left or right side of the same (two sides in total) or even in a case where there are electrode terminals at one side of the display panel and both of the left and right sides of the same (three sides in total), a display panel socket capable of arranging the film attachment boards at appropriate positions so that the positions can be adjusted can be provided.
Further preferably, the panel positioning means has panel positioning pieces which are provided near two of the crossing portions of the elongated grooves and engaged with corner portions of the substrate of the display panel and a substrate pressing means for pressing the other corner portions of the display panel toward the panel positioning piece; and the substrate pressing means can be respectively detachably attached to the two of the crossing portions of the elongated grooves and two corner portions of the socket body facing each other in the diagonal direction.
According to the above configuration, by pressing the corner portions of the display panel toward the panel positioning piece by the substrate pressing means, the display panel can be reliably positioned and held on the socket body and, at the same time, the display panel can be easily attached and detached to and from respect to the socket body. In addition, the substrate pressing means can be detachably attached to two corner portions of the socket body facing the two of the crossing portions of the elongated groove in the diagonal direction, therefore the display panel can be biased in a direction of suitable panel positioning pieces corresponding to display panels having different electrode terminal arrangements.
Preferably, the film attachment board is a printed wiring board having a wiring pattern which is connected to the contactors of the flexible wiring board.
According to the above configuration, since the film attachment board is a printed wiring board having the wiring pattern which is connected to the contactors of the flexible wiring board, it becomes unnecessary to separately provide a printed wiring board for sending signals to the flexible wiring board.
Further preferably, the biasing spring comprises a linear or plate shape spring piece engaged with a projection projected from the top surface of the end piece; and the spring holding portion has projections engaged with the two ends of the spring piece.
According to the above configuration, the linear or plate shape spring piece serving as the biasing spring can be easily arranged at a corner portion of socket body without interference with the adjustment member, therefore a display panel socket which is compact and enables provision of the film attachment boards at appropriate portions adjustable in position corresponding to the arrangement of the electrode terminals of the display panel can be provided.